全文获取类型
收费全文 | 36179篇 |
免费 | 934篇 |
国内免费 | 1316篇 |
专业分类
化学 | 5056篇 |
晶体学 | 940篇 |
力学 | 590篇 |
综合类 | 126篇 |
数学 | 27029篇 |
物理学 | 4688篇 |
出版年
2023年 | 165篇 |
2022年 | 232篇 |
2021年 | 264篇 |
2020年 | 308篇 |
2019年 | 682篇 |
2018年 | 737篇 |
2017年 | 524篇 |
2016年 | 566篇 |
2015年 | 537篇 |
2014年 | 1052篇 |
2013年 | 2355篇 |
2012年 | 1032篇 |
2011年 | 2257篇 |
2010年 | 2013篇 |
2009年 | 2578篇 |
2008年 | 2640篇 |
2007年 | 2548篇 |
2006年 | 1879篇 |
2005年 | 1606篇 |
2004年 | 1395篇 |
2003年 | 1180篇 |
2002年 | 1364篇 |
2001年 | 1135篇 |
2000年 | 1057篇 |
1999年 | 1188篇 |
1998年 | 1012篇 |
1997年 | 761篇 |
1996年 | 606篇 |
1995年 | 570篇 |
1994年 | 556篇 |
1993年 | 382篇 |
1992年 | 381篇 |
1991年 | 268篇 |
1990年 | 271篇 |
1989年 | 245篇 |
1988年 | 171篇 |
1987年 | 172篇 |
1986年 | 133篇 |
1985年 | 229篇 |
1984年 | 169篇 |
1983年 | 96篇 |
1982年 | 160篇 |
1981年 | 165篇 |
1980年 | 159篇 |
1979年 | 95篇 |
1978年 | 149篇 |
1977年 | 119篇 |
1976年 | 105篇 |
1975年 | 47篇 |
1974年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A.J.?Lpez-Moreno 《Acta Mathematica Hungarica》2005,106(4):343-354
Summary We obtain preservation inequalities for Lipschitz constants of higher order in simultaneous approximation processes by Bernstein type operators. From such inequalities we derive the preservation of the corresponding Lipschitz spaces. 相似文献
72.
Nobuhiro Honda 《Mathematische Nachrichten》2003,256(1):48-57
In a previous paper of the same title the author gave a generalization of the constrution of Donaldson–Friedman, to prove the existence of twistor spaces of n CP 2 with a special kind of divisors. In the present paper, we consider its equivariant version. When n = 3, this gives another proof of the existence of degenerate double solid with C *–action, and we show that the branch quartic surface is birational to an elliptic ruled surface. In case n ≥ 4, this yields new Moishezon twistor spaces with C *–action, which is shown to be the most degenerate ones among twistor spaces studied by Campana and Kreußler. 相似文献
73.
Kunyu Guo 《Journal of Functional Analysis》2004,213(2):380-411
This paper mainly concerns defect operators and defect functions of Hardy submodules, Bergman submodules over the unit ball, and Hardy submodules over the polydisk. The defect operator (function) carries key information about operator theory (function theory) and structure of analytic submodules. The problem when a submodule has finite defect is attacked for both Hardy submodules and Bergman submodules. Our interest will be in submodules generated by polynomials. The reason for choosing such submodules is to understand the interaction of operator theory, function theory and algebraic geometry. 相似文献
74.
We show that there are close relations between extremal problems in dual Brunn-Minkowski theory and isotropic-type properties for some Borel measures on the sphere. The methods we use allow us to obtain similar results in the context of Firey-Brunn-Minkowski theory. We also study reverse inequalities for dual mixed volumes which are related with classical positions, such as ?-position or isotropic position. 相似文献
75.
Using the theory of noncommutative symmetric functions, we introduce the higher order peak algebras (Sym(N))N≥1, a sequence of graded Hopf algebras which contain the descent algebra and the usual peak algebra as initial cases (N=1 and N=2). We compute their Hilbert series, introduce and study several combinatorial bases, and establish various algebraic identities
related to the multisection of formal power series with noncommutative coefficients.
Received November 19, 2004 相似文献
76.
We extend the matrix version of Cochran's statistical theorem to outer inverses of a matrix. As applications, we investigate the Wishartness and independence of matrix quadratic forms for Kronecker product covariance structures. 相似文献
77.
78.
An attempt is made to present a simple theoretical analysis of the energy-wave vector dispersion relation of the conduction electrons in heavily doped non-parabolic semiconductors forming band tails. We observe that the complex energy spectrum in doped small-gap materials whose unperturbed conduction band is described by the three band model of Kane is due to the interaction of the impurity atoms in the tail with the spin-orbit splitting constant of the valence band (Δ), For band-gap (Eg)<Δ the imaginary part predominates which tails in to the conduction band. For the opposite inequality the real part comes in to play which tails in to the split-off band. In the absence of the band tailing effect, the imaginary part of the complex energy spectrum vanishes and the same is also true for doped two-band Kane-type and parabolic energy bands respectively. The present formulation helps us in investigating the Boltzmann transport equation dependent transport properties of degenerate semiconductors and are expected to agree better with experiments. The well-known results of unperturbed three and two band models of Kane together with wide-gap parabolic energy bands have been obtained as special cases of our generalized analysis under certain limiting conditions. 相似文献
79.
80.
该文讨论一类带有奇异系数的双重调和方程{△^2u-μu/|x|^s=f(x,u),x∈Ω,u=δu/δv=0,x∈δΩ,这里Ω包含R^N是包含0的有界光滑区域,u∈H0^2(Ω),μ∈R是参数,0≤s≤2,△^2=△△表示双重拉普拉斯算子,当f(x,u)=u^p,p=2N/N-4时,上述问题就是一个临界双重调和问题,该文运用Sobolev-Hardy不等式和变分方法,得到它的解的存在性的一些结果。 相似文献